A. Field of the Invention
The present invention relates to percussion musical instruments, specifically drums. More particularly, the invention relates to a drumhead construction having improved acoustical characteristics.
B. Description of Background Art
A variety of drums are used by orchestras, bands and other such musical groups Drum types commonly used by musicians include kettle drums, also known as tympani, base or kick drums, and snare drums. All of these drums include one or two heads, each having a membrane made of an animal skin or synthetic polymer sheet. The membrane is held in tension over the open end of a hollow cylindrical shell, the outer surface of the membrane being used as a striking or batter surface which is impacted by a drumstick, mallet or hand, causing the drumhead and air column within the shell to vibrate at audible frequencies.
The fundamental vibration frequency, harmonics or overtones of the fundamental vibration frequency, and decay or dampening time of sounds produced by a drum are determined primarily by characteristic or normal vibration modes excited in the drumhead membrane when it is struck by a drumstick, mallet, hand or other object. Vibration frequencies and resonance or dampening characteristics of the drumhead vibration modes are in turn determined in part by the diameter, weight per unit area, compliance or elasticity, and other such properties of the drumhead membrane. Drumhead vibration frequencies are also determined by the amount of tension exerted on the drumhead membrane. This tension is usually controlled by means of an adjustable hoop attached to the drumhead membrane and clamped to the shell. Therefore, producing desired tones from a drum requires that tension in the drumhead be accurately and uniformly adjusted by the drum hoop tensioning means.
Since the required tension is often times quite large, polyester film, because of its high strength, resistance to weather changes, consistency and tone quality, is the preferred material for the manufacture of drumhead membranes. Unfortunately, polyester films such as MYLAR.TM., when struck with a drumstick, produce undesirable high-frequency resonant overtones which may have a substantially long decay time. The task of reducing or eliminating undesirable overtones creates substantial problems in tuning drumheads, and in the "miking" (picking up sounds with a microphone). amplification and recording of drum sounds produced in a concert hall or other such venue.
In an effort to decrease the amplitude of undesirable high frequency drum resonances, and/or to dampen or decrease their resonant decay times, drummers and sound engineers have heretofore resorted to a variety of less than optimum methods.
One make-shift approach to dampening undesirable drumhead overtones consists of placing or attaching pieces of sound deadening material on the outside surface of a drumhead. Facial tissue, felt, paper towels and cloth have been used for this purpose, but the results achieved are inconsistent at best. Also, from an aesthetic point of view, pieces of paper or cloth taped to a drumhead are very unsightly, for both live performances and televised concerts.
Taping towels, paper or cloth to one area of a drumhead to reduce the amplitude and duration of undesirable overtones also has the unwanted consequences of over-muffling one area of the drumhead, while having little effect on the remainder of the head. This results in the production of a somewhat unbalanced set of frequencies, owing to the fact that the dampening of overtones is confined to a localized area of the drumhead contacted by the dampening materials. A loss of overall tone quality and musical effect is the usual result. Also, the drummer is presented with the problem of avoiding the muffled area when striking the drumhead. This problem is aggravated when individual drums of a large set of drums, sometimes as many as ten, must be struck in rapid succession.
Another approach to muffling drumhead overtones, used primarily on base drums having an open end, consists of placing a pillow or blanket inside the drum, in contact with the inside surface of the drumhead. At best, this method results in unpredictable or weird sounds to be produced by the drum.
In an effort to solve the harmonic ringing problem, some manufacturers of drumheads have constructed laminated drumheads having multiple plies. An inherent problem with such drumheads is the dull, over-muffled sound produced by the drums. Also, it is difficult to maintain the same relative tension in the two plies. The result is an inconsistent product.
Other approaches to drumhead overtone dampening have included laminating foam or rubber rings to an inner surface in the drumhead. However, the weight of such materials prevents the drumhead from vibrating in a desired fashion. Moreover, the tone quality and musical effect are degraded by such muffling rings.
Since no completely satisfactory solution to the problem of drumhead ringing control existed heretofore, the present invention was conceived of to solve that problem.